Compressor unloader and check valve unit

ABSTRACT

A COMPRESSOR UNLOADER AND CHECK VALVE UNIT COMPRISING A VALVE BODY HAVING A PRESSURE INLET PORT FOR CONNECTION THERETO OF A LINE FROM A COMPRESSOR, A PRESSURE OUTLET PORT FOR CONNECTION THERETO OF A LINE TO AN ACCUMULATOR, AND AN EXHAUST VENT PORT. A VENT PORT VALVE MEMBER IS PROVIDED IN THE BODY, THIS VALVE MEMBER BEING BIASED TOWARD A CLOSED POSITION FOR BLOCKING COMMUNICATION BETWEEN THE INLET PORT AND THE VENT PORT, AND BEING OPENED VIA A PISTON IN THE BODY UNDER CONTROL OF A PILOT VALVE IN RESPONSE TO INCREASE OF PRESSURE IN THE OUTLET PORT. A CHECK VALVE IS PROVIDED IN THE BODY WHICH IS BIASED TOWARD A CLOSED POSITION FOR BLOCKING COMMUNICATION BETWEEN THE INLET AND OUTLET PORTS.

United States Patent [72] Inventor Joseph L. Krechel Chesterfield, Mo. (P.O. Box 122, High Rise, Mo. 63049) [2]] Appl. No. 869,234 [22] Filed Oct. 24, 1969 [45] Patented June 28, 1971 [54] COMPRESSOR UNLOADER AND CHECK VALVE UNIT 3 Claims, 3 Drawing Figs.

[52] US. Cl 137/116, 137/118, 137/1'19 [51] Int. Cl 605d 16/10 [50] Field ofSearch 137/115, 116,116.3,116.5,1l8,119

[56] References Cited UNITED STATES PATENTS 2,622,611 12/1952 Stark 137/116 3,011,506 12/1961 Schwartz 137/118 3,073,332 1/1963 Strader 137/119 3,224,456 12/1965 Klein 1. 137/115 Primary Examiner-William F. ODea Assistant Examiner-William H. Wright Attorney1(oenig, Senniger, Powers and Leavitt ABSTRACT: A compressor unloader and check valve unit comprising a valve body having a pressure inlet port for connection thereto of a line from a compressor, a pressure outlet- COMPRESSOR UNLOADER AND CHECK VALVE UNIT BACKGROUND OF THE INVENTION This invention relates to valves, and more particularly to a compressor unloader and check valve unit. The invention is particularly applicable to compressor installations wherein it is desired that the compressor continue to operate after the system is up to pressure.

Installations wherein it is desirable that the compressor continue to operate after the system has been charged to operating pressure are known, e.g., compressed air supply systems for vehicular air brakes. In these systems, the conventional compressor unloaders are designed to keep the suction line of the compressor open when the accumulator or receiver is up to pressure, with a check valve closing the line to the accumulator from the discharge of the compressor. The result is that the compressor free wheels, drawing air in through the suction line and then pushingit back out the same line again. This method of operation can be undesirable in that lubricating oil used in the compressor can tend to creep up around and onto the top of the piston of the compressor. The lubricant can subsequently burn off or pass into the compressed air system wherein its presence is highly undesirable.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a compressor unloading and check valve unit which will permit the compressor to continue to operate in its normal manner when unloaded. It is an advantage of the present invention that the unloading and check valve and pilot or control valve are in one unit. This improves the structural integrity of this system by minimizing the number of sites for leakage. It is believed that in the past, those skilled in the art have tended to separate the various components of the valve because of a fear of the sensitivity of the pilot valve to compressor pulsations which might be transmitted to and cause the check valve and unloader to pulsate. It is an object of the present invention to provide such a valve assembly wherein the pilot valve is not sensitive to pulsations. It is a further object of the present invention to provide such a compressor unloading and check valve assembly without any auxiliary sensing lines.

The present invention accordingly involves a valve for a compressor system which includes a body having a pressure inlet port, a pressure outlet port, and an exhaust vent port. A vent port valve member is slidably mounted in the housing for movement between a position closing the exhaust vent port and a position wherein the exhaust vent port is opened. A piston is slidably mounted in the housing and a piston rod connects the vent port valve member and the piston. The piston is biased toward a position wherein the vent port valve member closes the exhaust vent port. A pressure chamber is provided in the body on the opposite side of the piston from the piston rod and has a first passage extending therefrom to a second passage in communication with the outlet port and also to a bleed to atmosphere. A pilot valve has a valve member controlling communication between the first passage and the second passage and between the first passage and the bleed to atmosphere. The pilot valve member is biased toward closed position closing off communication between the first and second passages until the outlet port pressure as communicated through the second passage reaches a predetermined amount overcoming the bias, causing the pilot valve member to open so as to supply pressure to the pressure chamber via the second and first passages. The first passage and the bleed to atmosphere are connected when the pilot valve member is closed so that pressure in the chamber may be bled to the atmosphere. A check valve member is slidably mounted in the housing for movement between a closed position blocking communication between the inlet port and the outlet port and an open position permitting communication therebetween. The check valve member is biased into closed position when the inlet pressure acting against it is below a certain value, as when the exhaust vent port is opened, whereby the inlet pres- LII sure is released through the exhaust vent port. Other objects and features will be in part apparent and in part pointed out hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a longitudinal cross-sectional view of a unit according to the instant invention showing the position of the various parts when the compressor is charging the system;

FIG. 2 is a view similar to FIG. 1 showing the position of the various parts of the unit when the system is up to pressure; and

FIG. 3 is a perspective of the unit as viewed from its left end in FIGS. 1 and 2.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, an unloader and check valve unit made according to the present invention is shown to comprise a body 1 having a lateral pressure inlet port 3, a lateral pressure outlet port 5 and a lateral exhaust vent port 7. The various ports are interconnected in the body via a bore 9 extending longitudinally through the body. A vent port valve member II, which may be of any suitable material, e.g., a fluorinated hydrocarbon such as that known in the trade as TEFLON, is slidably mounted in bore 9 of body 1 for movement between a position closing the exhaust vent port 7 as shown in FIG. 1 and a position wherein the exhaust vent port is open as shown in FIG. 2. As illustrated, the vent port valve member 11 closes exhaust vent port 7 by engagement with a valve seat 13 formed by a shoulder in bore 9. On the opposite side of exhaust vent port 7 from the valve member 11 is a partition 15 having a central opening 17.

Extending through this opening 17 is a piston rod 19. Piston rod 19 is connected at one end to valve member 11, and is connected at its opposite end to a piston 21 slidably mounted in a cylinder 22 formed in body 1. Piston 21 has an annular groove 23 in which an O-ring 25 is fitted to seal against the wall of cylinder 22. A coil compression spring 27 reacting from partition 15 biases piston 21 toward the right, toward a position wherein valve member 11 engages seat 13 closing exhaust vent port 7 from the remainder of the system.

The space in cylinder 22 at the outer end of the cylinder on the right of the piston constitutes a pressure chamber 29. A first passage or control port 31 extends from this pressure chamber 29 to a second passage 33 which is in communication with outlet port 5 and also extends to a bleed 35 to atmosphere. The bleed 35 and part of passage 33 are in a pilot valve 37 secured to one end of the body 1 as indicated at 39.

Pilot valve 37 includes a spring 43 and a ball 45. A guide rod 47 extends from ball 45 at one end through the atmospheric bleed 35 at the other end and has a collar 49 between its ends. Spring 43 acts against collar 49 on guide rod 47 and biases guide rod 47 to push ball 45 toward the position closing the valve 37, i.e., it pushes the ball 45 against a seat 51. A tubular fitting 53 having an inwardly extending stop flange 55 thereon is positioned around guide rod 47 so as to limit the downward movement of guide rod 47 by the bottom side of collar 49 engaging stop flange 55. The end of spring 43 opposite that pushing against collar 49 engages the inward end of a sleeve 57 threadably engaged with fitting 53 and having a passage therethrough which forms part of the bleed 35 to atmosphere and through which guide rod 47 extends.

Spring 43 biases ball 45 toward the closed position, i.e., against seat 51, until the pressure in outlet port 5 as communicated through second passage 33 reaches a predetermined amount, which is sufficient to overcome the force exerted by spring 43. Pilot valve 37 then opens by reason of the ball 45 being pushed off seat 51 by the pressure-Pressure is then transmitted to pressure chamber 29 via passages 33 and 31. At the same time, ball 45 is pushed against an upper seat 59 provided on fitting 53 closing communication between passages 31 and 33 and the bleed 35 to atmosphere. It will be appreciated that when the ball 45 is in position wherein communication between passages 31 and 33 is blocked, communication is open between passage 31 and bleed 35 to atmosphere so that pressure in chamber 29 may be bled to the atmosphere.

A check valve member 61 is slidably mounted in body 1 for movement between a close position engaging a seat 63 and thereby blocking communication between the inlet port 3 and the outlet port 5, as shown in FIG. 2, and an open position permitting communication therebetween as shown in FIG 1. Valve member 61 may be formed of any suitable material, for example, the same material as valve member 11. Spring 65 biases the check valve member 61 toward its closed position. As shown, the spring 65 reacts from the left end of body 1 which may be formed as a head threaded on the body of the housing or attached thereto via a flanged connection such as used to attach the pilot valve assembly to the other end of body 1. Because spring 65 biases check valve member 61 into closed position from the outlet port 5 side, the outlet port pressure as communicated back through outlet port 5 assists spring 65 in biasing valve member 61 into the closed position.

The discharge line from a compressor (not shown) is connected to inlet port 3. OUtlet port 5 is connected to the intake of an accumulator or receiver for the system. When necessary, e.g., for noise abatement purposes, a muffler may be attached to exhaust vent port 7.

FIG. 1 shows the position of the various parts of the valve when the compressor is charging the accumulator or receiver. The inlet pressure through port 3 is sufficient to push check valve member 61 to the left against the action of spring 65, thereby permitting communication between inlet port 3 and outlet port 5 so that the accumulator or receiver may be charged. At the same time, the outlet port pressure as communicated via passage 33 is below that required to lift ball 45 off seat 51. Hence, any pressure in chamber 29 is vented to atmosphere via passage 31 and bleed 35 to atmosphere. Because of this, there is no force resisting the action of spring 27 against piston 21 biasing the piston 21 to the right which causes valve member 11 to engage against seat 13 closing the exhaust vent port 7.

Referring now to FIG. 2, as the accumulator or receiver comes up to the desired pressure, the outlet port pressure rises and when the pressure as transmitted through passage 33 has reached a predetermined level, corresponding to the desired operating pressure in the receiver, ball 45 is raised from seat 51 permitting communication between passage 33 and passage 31. At the same time ball 45 rises against upper seat 59 closing off the bleed 35 to atmosphere. The outlet port pressure as communicated via passage 33 and passage 31 into pressure chamber 29 pushes piston 21 to the left against the biasing force of spring 27. This causes vent port valve member 11 to open off seat 13 so that the inlet port pressure drops as fluid starts to pass around valve member 11 and out exhaust vent port 7. Because of the resultant drop in inlet port pressure, acting against the face of valve member 61, check valve member 61 snaps to the right against seat 63 blocking communication between the inlet port 3 and outlet port 5, thus effectively sealing the accumulator or receiver from the compressor. The compressor will continue to operate in the normal manner except that its discharge will enter the valve inlet port 3 and be directed to atmosphere through exhaust vent port 7. This will continue until the pressure in the accumulator or receiver has dropped through usage, resulting in a corresponding drop in the outlet port pressure of the valve assembly. This drop in pressure is transmitted through passage 33, with the result that when the biasing action of spring 43 is sufficient to overcome the communicated pressure, ball 45 will reseat against seat 51. This will open the bleed 35, causing the pressure in pressure chamber 29 to be released. As a result, spring 27 will push piston 21 to the right causing valve 11 to reseat against seat 13 again closing the exhaust vent port. This results in an increase in inlet port pressure acting against the face of valve member 61 pushing it to the left and thus opening communication between the inlet port 3 an outlet port 5 so that the accumulator or receiver can be recharged to pressure.

In past assemblies, a pilot valve corresponding to pilot valve 37 has always been isolated from a check valve in a compressor control system, the check valve corresponding to valve 61. For example, the pilot valve might be used to keep open the suction valves to the compressor when the accumulator was up to pressure. This separation of systems was because those skilled in the art were fearful of the sensitivity of the pilot valve to compressor pulsation and the possibility that the pulsation would be transmitted to the check valve and unloader and cause the check valve and unloader to pulsate. Pilot valve 37 is not sensitive to pulsations in the present invention. This is believed due to the position of the passage 33 which extends between the outlet port and pilot valve 37. This position of passage 33 seems to dampen any pulsations which might be felt.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes can be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense.

lclaim:

l. A valve assembly for a compressor system comprising a body having a pressure inlet port, a pressure outlet port, and an exhaust vent port; a vent port valve member slidably mounted in the housing for movement between a position closing the exhaust vent port and a position wherein the exhaust vent port is open; a piston slidably mounted in the body; a piston rod connecting the vent port valve member and the piston; means biasing the piston toward a position wherein the vent port valve member closes the exhaust vent port; a pressure chamber on the opposite side of the piston from the piston rod with a first passage extending therefrom to a second passage in communication with the outlet port, and also to a bleed to atmosphere; a pilot valve having a valve member controlling communication between the first passage and the second passage and between the first passage and the bleed to atmosphere; means biasing said pilot valve member toward a closed position closing off communication between the first and second passages until the outlet port pressure as communicated through the second passage reaches a predetermined value overcoming the bias and causing said pilot valve member to open so as to supply pressure to the pressure chamber via the second and first passages, the first passage and the bleed to atmosphere being connected when the pilot valve member is closed so that pressure in said chamber may be bled to the atmosphere; a check valve member slidably mounted in the body between a closed position blocking communication between the inlet port and the outlet port and an open position permitting communication therebetween; and means biasing said check valve member into closed position when the inlet pressure acting against it is below a certain value, as when the exhaust vent port is open, whereby the inlet pressure is released through the exhaust vent port.

2. The valve of claim 1 wherein the check valve member is biased into closed position blocking communication between the inlet port and the outlet port from the outlet port side whereby the outlet port pressure can assist in biasing the check valve member into closed position.

3. A compressor unloader and check valve assembly comprising a body having a bore, a lateral pressure inlet port, a pressure outlet port and an exhaust vent port in communication with the bore, a vent port valve member slidable in the bore for movement between a closed position engaging a seat between the inlet and vent ports and an open position establishing communication between the inlet and vent ports, said body having a cylinder in line with the bore, a piston rod extending from said vent port valve member into said cylinder and having a piston thereon slidable in the cylinder, spring means acting on the piston biasing the vent port valve toward its closed position, a pilot valve at the outer end of the cylinder having a bleed to atmosphere, a control port between the value overcoming the bias and causing the pilot valve member to move to a second position opening said passage and closing said bleed so as to supply pressure to the cylinder to open the vent port valve, a check valve seat in the bore between the inlet and outlet ports, a check valve slidable in the bore toward and away from said seat, and spring means biasing the check valve toward its said seat. 

